Several distinct projects will be investigated: (1) Examination of regulatory molecules in control of transcription and transcription termination (attenuation) at the primary promoter (P1) and an internal promoter (P2) of the Salmonella histidine operon. (2) Possible interactions in vivo of the Salmonella histidine biosynthetic enzymes and tRNA-HIS ligase. (3) Relationships of various components of the phosphoenolpyruvate: sugar phosphotransferase system to bacterial chemotaxis to sugars. (4) Possible synergisms and antagonisms of microbial species in cancer patients with greatly simplified bacterial flora. (5) Interaction of polyamines and nitrous acid in relation to mutagenesis and carcinogenesis.